So as stated in the title im having the one issue that most people have when it comes to these harnesses. Well this is where my problem begins, so as most threads say online to take the spare terminal on the icm and and run a wire to the shock tower tach plug. as soon as i hook up the wire to the lonely blue tach wire on the tower it shuts off. if the car is running and i touch it to the blue tach wire the car shuts off. as soon as the wire is removed is starts up. its on the right terminal in the dizzy, everything is ran how its suppose to. i have 2 different obd1 ecus also both have the same return when used, there is no difference at all still no tach and as soon as the connection is made the car dies. Other than that the car runs great with the obd1 ecu. This is in a 2000 civic ex coupe. any help would be great. Thank you

 

my guess... you are shorting out the distributor tach signal, likely your shock tower plug location is incorrect. (double check everything)

start with disconnecting the shock tower end of the wire, then connecting the wire to the distributor. (sounds stupid but this checks that the routing of the wire isn't causing the problem, ie shorting on something)

after that triple check the shock tower plug location.

after that make sure that the shock tower plug's wire goes the right place and isn't connected to something else for some reason. (this step begins to suck)

if you have a DMM/DVM/volt meter
-make sure that there is no voltage on the shock tower pin
-make sure that the pin does not have ground on it, (ohms setting)
if there is either (ground or voltage), something is wrong from the shock tower to the cluster or the speedo is bad.
if your meter has a Hz or frequency input, the tach signal is a 0-5v signal (or 0-12, I get the VSS and Tach mixed up)
-connect to the distributor and make sure that the value rises with the engine RPM (makes sure that your distributor is wired correct)